madson



Patented Jan. 10, 1928.

1,655,9ltl

LEO A. MADSON, 0F ELK RIVER, MINNESOTA.

RADIO LOUD SPEAKER.

Application filed. March I, 1924. Seria No. 696,290.

This invention relates to. im 'n oveiuents in loud speakers particularly adapted for use to receive radio broadcasting, and more particularly relates to such loud speakers em" ploying a radio phone unit having a vibratory plate mounted therein adapted to actuate the usual diaphragm, such "for ii'istanco, as is employed in the nelldtnouui .l'laldwiu type C unit.

The particular object oi? this invention is to provide a means operable in conjunction with such a phone or loud speaker unit tlfor the purpose of equalizing the oscillations oil? the vibratory plate mounted therein, thereby greatly increasing the volunm and strength of the incoming signals when used with a receiving set.

Other objects will appear :l'rom the following description and the accompanying drawings and will be pointed out in the annexed claims.

In the drawings there has been disclosed a structure designed to carry out the various objects of the invention, but it is to be understood that the invention is not confined to the exact features shown, as various changes may be made within the scope of the claims which follow.

In the accompanying drawings forming a part of this specification,

Figure 1 is a view in side elevation of a loud speaker embodying my invention;

Figure 2 is an enlarged detail sectional view of the lower portion thereof, showing a standard type of phone unit mounted therein and also showing my invention applied thereto.

In the selected embodiment of the invention here shown there is illustrated a loud speaker comprising the usual born 4 mounted in the upper portion or cap 5 of a cylindrical housing 6 which is suitably mounted in a base 7, as shown in Figure l. A. radio phone unit, of ordinary construction, is preterably mounted. in the upper portion of the cylindrical housing 6, as shown in Figure 2. The type of phone unit here shown comprises a magnet 8 having a coil 9 mounted therein by means of U-shaped brackets 11 secured thereto. The coil and magnet are secured to a perforated disk 12 which is seated in a sleeve 13 adapted to be fitted within the upper portion of the housing 6, and which is suitably secured thereto. This sleeve is preferably of non-conductive Ina-- terial.

The usual diaphragm 14; is shown seated on the disk 12 and has a link 15 connecting it with one end oi an armature plate 16 mounted within the coil 9 in the usual manner. This plate is adapted for vibratory movement when the coil 9 is energized, as when the phone unit is functioning, thereby transmitting a similar movement to the diaphragm which causes the incoming signals to become audible. In the operation. of a radio phone unit. such as the one above de scribed, l have found that the oscillations of the plate 16 are not uniform or equal, caused by the tension oil: the diapln'agm tendhip; to exert a slight upward. pull. on the plate through the link 15. I have also found from actual. experience that when the action of the vibratory armature plate 1.6 is equal ized, the signal strength will be greatly increased, and the primary purpose of this invention, therefore, is to provide means operable in conjunction with such a unit whereby the action of the plate will be substantially equalized.

Such means preferably consists in the provision of a coil or winding 17 mounted within the housing 6 beneath the radio phone unit. This winding is encased within a suitable insulation 18 and has an iron core 19 concentrically mounted therein, having its lower end portion resting on the bottom wall. of the housing and having its upper end bearing against one of the pole pieces 11 supporting the coil 9. A thin sheet of insulating material 21 interposed between the bracket 11 and the end of the core 19 to prevent short-circuiting, and the lower end of the core is similarly insulated from the housing wall. Conductors 22 and 23 lead from the winding 17 and outwardly pass from the housing 6 through an insulating bushing 9A, for connection with a suitable source oil? energy such. as a battery.

l Vlieu current is passed through the coil 17, the core 19 will become energized and will l'unction as a magnet, scattering additional lines of force tln'oughout the appa ratus which, obviously will be greater in the intermediate portion of the casing ll beneath the coil 9 and permanent magnet 8 of the speaker unit. its a result of the magnetic lines of force thus set up within the apparatus being relatively stronger in the intermediate portion of the casing 6 than in the upper portion thereof, the armature plate 16 will. beinfluenced thereby and the I resultant downward pull exertedthereon will ed thereon which be snflieient to overcome a portion adjacent the core 19 than it is'away from it, thereby influencing-the armature plate 16 and cansing an additional downward pull to be'exertis transmitted to the diaphragm 14 by the link 15.

In various ways the details of construction herein shown and described may be inodilied and still be within the seope of my invention.

I claim asiny invention:

LA radio loud speaker comprising a phone unit l'iaving a diaphragm, a. magnet coil and a vibrating armature plate between the upper and lower portions 0; said coil and connected with said diaphragm for vibrating it when said coil is energized, and a supplementarymagnet arranged adjacent to saidcoil and adapted to create magnetic lines of forceto attract and exert a don" ward pull on said armature plate and thereby compensate for the tensiona'l resistance of said diaphragm to the downward movement of said armature plate.

2; A radlo loud sneaker comprising a phone unit having a diaphragm a magnet. and a vlloratlng armature having means connecting it with said diaphragm, and means for overcoming the tensional resistance ol' said diaphragn'i to the ll'lOVGlUOUt of said armature in one direction, said means co1n prising a coil connected with a source of electrical energy and a core in said coil having one end adjacent said vibrating; arinatu re.

3. A adio loud speaker comprising a phone unit having a diaphragm, a magnet coil and a vibrating armature plate between the upper and lower portions of said coil and conneeieii with said diaphragnn for vibrating it when said coil is energ zed, a supplementary niagi'iet arrann'rd beneath and adjacent to said coil and comprising an insulated winding. a core mneentrieally mounted therein. the upper end of eaid core being; adjacent said (Oil and ineulated thri'eiron said s-nppleinentary nnignel being: adapted to create lines of force and attract said armature plate and coiniiiensate for the tensional resistance of said diaphragm to the downward movement of said plate.

In witness whereof, I have hereunto set my hand this 27th day of February 1924.

LEO fr. MADSON. 

